Exposure-meter.



G/L. HARVEY.

EXPOSURE METER.

APPLICATION FII .ED MAR. 29| |916.

1 1 86 098. Patented June 6, 1916.

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EXPOSURE METER.

STOP NUMBERS.

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Patented June 6, 1916.

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Iam/emi??? @Page lEzrf/gy UNITED sTATEs PATENT oEEroE.

GEORGE L.IIARVEY, OF CHICAGO, ILLINOIS.

EXPOSURE-METER.

Specification of Letters Patent.

Substitute for application Serial No. 55,504, led October 12, 1915. Thisapplication filed March 29, 1916.

, Serial No. 87,451.

To all whom t may. concern:

Be it known that I, GEORGE L. HARVEY, a citizen of the United States,and resident of Illinois, have invented certain new and usefulImprovements in Exposure-Meters, of which the following is aspecification.

My invention relatesY to the art of photography and has particularreference to a novel exposure meter.

This application is a substitute for my application Serial No. 55,504,filed October The development of the art of photography has been .sogreat that the use of cameras and photographing devices by ama.

teurs has become practically general through out the world.1 Thegreatest proportion or volume of photography is practised by amateurs,and part1cularly by amateurs who have little conception of the scope orcapac-y ity of the cameras with which they are operating, with relationto the speed of plates,

light condition, etc.

I am aware that exposure meters, or devices intended as guides for useby amateurs,

have been suggested and manyforms there-N of are available. All of suchdevices, however, require considerable manipulation as to the mechanicalfeatures, and, 1n some instances, computations are required in order to'arrive at the desired result. The consequence is that many amateurs,rather than attempt these adjustments or computations, rely upon theirjudgmentto the detriment of the final result.

An object in the construction of the present device is to provide anexposure meter which shall have the following points of advantage:first, extreme simplicity, to the end that the operator is required tomove but a single part in order to arrive at the desired result, itbeing assumed thatthe meter has been set for the location as tol'ati--tude and the time of the year, as to summer or winter; second,flexibility `as to all conditions of light, speed of plates, etc.;`third, unlimited capacity as to the latitude or general'lgeographiclocation, and fourth, cheapness in cost of construction andcompactnessin its final form.

The invention involves the use of a thin paper or card-board' envelop orreceptacle, within which are mounted two slides, one of which need beadjusted but once in a season, when in the same geographic location, theother of which is adapted for movement t to arrive at the proper timefor exposure of Chicago, 1n the county of Cook and State of 'stood byreference to the accompanying' drawings, wherein- Figure 1 is a View ofthe blank from which the incasing folder is formed; Fig. 2 is a similarview of the slide by means of which the different computations arearrived at; Fig. 3 is a view of the slide which provides the adjustmentfor different geographical locations; F ig. 4 is an assembled View ofthe device showing the `side from which the computations are secured;Fig. 5 is a view of the device from its reverse side; Fig. 6 is a viewof the reverse sidevof the slide shown in Fig. 2, and Fig. 7 is asection through the assembled device taken on the line 7-,7 of Fig. 5I.

Referring more particularly to the drawings, it will be seen that Iprovide a blank 10, which is notched atll, 12, 13, and scored at 14, 15.The. scoring permits of the blank beingv doubled on itself in suchmanner that the notches 11, 12, 13 are in register to provide forengagement of the computation slide when the same is inserted betweenthe folded portions of the blank. In the leaf 16, I provide a narrowslit or window 17 vin the leaf 18, I provide a rectangular win- PatentedJune e, 1916.- l

to the means for arriving at computations, f

but acts as a spacer between the two comput ing slides. In all Lof thedevices known to me which involve the use of two or more moving parts, adifficulty in the operation thereof has been in that4 one ofv saidmovable part-s might be set as desired, -but a movement of the secondmovable part would have atendency to change the adjustment of the. firstpart. This I have corrected by the employment of a sheet or filleroccupying the space between the two movable parts.

The window openings 19 and 21 are closed by sheets of transparentmaterial 23, 29,such as Celluloid or isinglass. At the upper end of theSection 1s I indicate, by printing, the

latitude or geographical location in which photography is commonlypractised in the northern hemisphere, together with the correspondinlocations of different localities, or cities, oth for summer and wmterexposures, this printed matter occupying indicated in Figs. 2 and 6, mayconsist of a` sheet of stili material, preferably of celluloid. Thisslide is lettered B, and on the face thereof, at a point near themiddle, I print descriptive matter as to the character of the light onthe day' or at" the time when the exposure is to be made. This slide, asindicated by the numeral 24, is `adapted to occupy the space within thefolded sections 16,

` 18,20, the printed matter as to the character of the light, whethersunlight, cloudy, etc., appearing in the window opening 19 at tht rightedge thereof, as viewed in Figs. 1 an 5.

On the opposite side ofv theA slide B, as in-` dicated in Fig. 6, isprinted, in suitable.

squares, certain lengths of time, divided into seconds, these numerals,when the meterl is properly adjusted, indicating to the user the'correct exposure u are seen through the slit 21 in the section 20 ofthe folder, as indicated in Fig. 4. One transverse row of figuresoccupies a single slit 21, and the vertical rows -of figuresare inalinement with the stop graduations apc pearing on section 20.

The slide lettered A, and which we have indicated by the numeral 25, isshorter than the slide B and is provided with a window opening 26 at oneedge thereof, which opening registers with the opening 17 in thelintermediate filler and permits the exposure of the light condition, asprinted'on slide B, and as indicated in Fig. 5. Printed'adjacent to thewindow' opening 26 is certain descriptive matter as to the character ofthe plates or films employed with their relative speed, the common'termsfor such speeds being indicated, as well as the technical descriptionthereof. A reinforced clip or fastener 27 is mounted in the upper end ofthe slide, this fastener coperating with and being guided in the slit 22in the section 18. The end 28 of the clip 'acts as a vpointer toindicate the section of the country or latitude at which the slide A isset, as best shown er the conditions fory which the meter has been set.The ligures in Fig. 5,-and is moved comparatively seldom. For instance,the slide A may be set for Chicago in the summertime, and if the userdoes not leave \-that vicinity during the summertime, the slide A neednot be moved during that time.

The parts which have been described are assembled, as best shown inFig.- 7. In that figure no attempt has been made to restrict the drawingto the actual size of the dev-ice, the showing being many times thickerthan the meter will be in its finished condition.

It will be noted that slide A does not project outside of the containeror envelop at any time, the adjustment being made by grasping thepointers 28, which project outside of the envelop, while the slide B isexosed at one end or the other at all times. y means of thisconstruction the adjustment of the shorter slide is not readily changedby jarring For handling, it being intended that theadjustment of thatslide shall remain more orv less permanent. The slide B is intended tobe adjusted foreach computation.

After the parts described have been properly located and the differentsections of the blank folded to the proper form, the entire envelop isinclosed in a wrapping of transparent material, the wrapping bein'g,indicated inFig. 7 by the numeral 30.

The material which` I employ for closing the window openings has adouble function, the function about to be described being of evengreater importance than that of a mere closure. It will be noted that atsome points the lower ends of the slides in their. vertical movement areopposite the lower edge of one ormore of the openings, and that thetendency is, in the absence of suitable means, for the slide to catch onthe edge of the opening. This diiculty is obviated in the presentconstruction by the simple expedient of closing the window opening bythe transparent sheet of material.

The o eration of the device is as follows, with re erence to the settingas shown in Figs. 4 and 5: Assuming that the desired location isFlorida, or 'a geographical location corresponding substantially tolatitude 30, and that the time at which the exposure is to. be madeis inthe summertime, the slide A is moved until the pointers 28 indicatethelower lefthand arrangement iof figures or letters, as indicated iFig.'5. The slide B is then moved until t e arrow, corresponding to thelight condition of the dayon which the exposure is to be made isopposite the plate or filmv which is to be used. In this case the deviceis set as indicating a dull, cloudy day and a late is used substantiallythe same as the lm pack having a plate speed of 100 H and D. The meteristhen turned over, and, on its back, as indicated by Fig. 4, will befound the proper speed of exposure for allstops. For instance, if a viewof the sea is to be taken and a stop corresponding to F8 is employed,the 'exposure will be one-thirtieth of a second. If

l a portrait is to be taken with a sixteen stop, the meterV indicatesthat an exposure of two seconds should be given. -Having once set theslide A for a geographical location and time of the year, it isunnecessary to change this slide until those conditions are changed.This slide having been adjusted, it then becomes necessary only toadjust the slide B to the light condition of the day on which theexposure is to be made, when on the reverse side of the meter will befound all conditions possible to be met, with the proper time forexposure in plain view.

It is obvious thatthe construction shown is capable of modification, andvsuch modifications as are within the scope of my claims, I considerywithin the spirit of my invention.

I claim: f

l. An exposure meter comprising a member provided with openings inopposite sides thereof and with symbols in coperative relation to therespective openings, and a slide movable with relation to said memberhaving upon opposite sides thereof syimbols which are visible throughthe respective openings, the symbols on one side of said member and saidslide being adapted to be correlated, whereby to set up correlativevalues between the symbols appearing on the opposite side of said memberand slide.

2. An exposure meter comprising an envelop provided with window openingsin opposite sides thereof and with symbols in cooperative relation tothe respective openings,v a pair of slides mounted within the envelop,one of the slides being provided with symbols on opposite sides thereof,the symbols on one ^side of the slide being exposed to View through thewindows in one side of the envelop,the other slide being provided withsymbols exposed to View through the window openings in the other side ofthe envelop, and said other slide having a window opening exposing toview the symbols on the adjacent side of saidfirst mentioned slide andincorrelation with the symbols on the second mentioned slide.

3. An exposure meter comprising an envelop formed of a blank doubled onitself to provide an intermediate sheet dividing the enveloplongitudinally, the opposite sides of the envelop being provided withwindow openings, the intermediate sheet having a window openingregistered with one of the" openings of the envelop, one side of theenvelop being provided with symbols adjacent the window opening therein,a slide mounted in one of the sections of the envelop and provided withsymbols upon vopposite sides thereof which are exposed to view throughthe windows in the respective opposite sides of the envelop, and asecondslide mounted in the other section of the envelop and provided withsymbols which are exposed to view through the opening in the adjacentside of the envelop, and also providedwith a window opening exposing t0view the symbols on the adjacent side of the first mentioned slide,which symbols are correlated with respect to the symbols on the secondmentioned slide.

4. An exposure meter, comprising in combination a memberhaving thereoncertain symbols indicating geographicalA locations and size of stops, amovable member having symbols indicating speed of plates and adapted tobe correlated with said geographical location symbols, and a secondmovable member having symbols indicating lightconditions and time, saidsymbols indicating the light conditions to be correlated with thesymbols indicating speed of plates on said first mentionedmovable memberIand the symbols indicating time of exposure to be correlated with thesymbols as 'to stops on said member, substantially vas described.

5. An exposure meter, comprising 1n combination a fixed chart having onone side certain symbols indicating geographical locations and on theother side symbols indicating size of stops, a movable chart havingsymbols indicating speed of plates and adapted to be correlated withsaid geographical location symbols, and a second movable chart havingsymbols indicating light conditions and time, said symbols indicatinglthe light conditions to be correlated with the symbols indicating.yspeed of plates on said first mentioned movable chart and the symbolsindicating time of exposure to be correlated with the symbols as tostops on said fixed chart, substantially as described.

6. VIn an exposure meter, the combination of an envelop having windowopenings in its sides, and having on one side adjacent to a windowopening certain symbols indicating geographical location, and on theother side and arranged rtransversely of the envelop certain symbolsindicating size of stops, a slide movable within said envelop,

said slide having thereon certain symbols indicating speed of plates, apointer o n said slide, said pointer being arranged to indicate certaingeographical locations as indicated on said envelo` said slide beingprovided with a windo opening, and a second slide having on one sidecertain designations as to light conditions, and on the other sidesymbols giving exposure times, said second slide being adapted to beassociated in said envelop in such manner that the symbols as to lightconditions may be viewed through the window in said first slide and saidsymbols as to exposure times to be cor- 4als related with thesymbols onthe envelop relating to the size of stops, substantially as described. yl

7. In an exposure meter, the combination of an element having in onewall thereof a plurality of sight apertures and adjacent to saidapertures designations of certain subjects to be photographed, stopnumbers arranged transversely of the element and in proximity to saidapertures, and a movable slide containing designations as to exposuretimes, and designations as to light conditions and speed of platesvisible from the o posite side lof said element, one of said sets odesignations appearing on the back of said slide, said designationsbeing'arranged to be correlated by movement of said slide to the endthat said slide may automatically display correct .exposure times fordifferent subjects and different sizes of stop openings, substantiallyas described.

8. In an exposure meter, the combination of an envelop having in oneWall thereof a plurality of apert-ures and provided between saidapertures, with designations of certain sub'ects to be hotogra hed,provision being ma e for the is versely of the envelop and in proximityto play o stop numbers trans-v said apertures, a slide movable withinsaid envelop, said slide containing designationsr from t e opposite sideof said envelop from that on which the designations of stop numv bersappear, substantially as described.

9. In an exposure indicator, the combination of a member providing aplurality of windows with a designation of the diiferent subjects to bephotographed located adjacent to each window, stop numbers displayed ina line parallel to said windows, and va chart movably mounted withrelation to said member, said chart having a plurality of rows ofexposure times dis layed thereon andy being adapted for adjustment as tolight conditions, a row of said exposure times being visible throughsaid windows, whereby at a single adjustment of said movable chart.there is visible the correct ex posure'times for a plurality of subjectsand for the different stops.

10. In an exposure meter, the combinavtion of a member having apluralityof sight apertures therein, the space adjoining said aperturescontaining designations of subjects to be photographed, a series ofstandard stop numbers disposed adjacent to said apertures, a slidecontaining on one face a table of exposure times, said slidev beingadapted to be associated with said member and arranged so that a line ofexposure times may bev viewed through 'said apertures, each exposuretime corresponding to a stop number in'line therewith, andsymbols as tolight conditions and speed .of plates, said symbolsbeing adapted to becorrelated by movement of said slide, substantally as described.

Signed at Chicago, Illinois, this 21st day of February, A. D.v 1916.

GEORGE L. HARVEY.

Witnesses: 4 T. D. BUTLER,

H. C. Jacos.

